Einstein figured out the theory of relativity in his head. Years later he developed the math and physics that proved his theory. Gretzky (especially), Orr, Mario were the best because of what was in their head. They had physical skills for sure but what made them great was their brains. No training could ever unleash the kind of mentality they had in other players. All those that think Orr or Gretzky would have needed years of training to dominate today fail to understand the mental abilities of these great players. Orr or Gretzky would take a few games or a few weeks to master the NHL in any era. That was their strength. Those that say that the very best players of the past would benefit from today's coaching and training fail to understand Gretzky and Orr had BETTER training than any player ever. Walter and Wayne himself developed training methods far beyond anything today. Doug and Bobby Orr too. Gretzky was doing training that NHLers don't get today when he was 8 or 9 years old. Sure they could have had weight training or power skating lessons that would make them stronger and a bit faster ut that would not be a very important factor in their success. Gretzky was possibly one of the very weakest players in the NHL as he garnered 4 Cups and 9 MVP trophies in a row. And the NHL was far more physical and violent than than it is today.
There are many on these boards that believe the fact that all players today get significant weight training means that everyone is stronger than the players in the past. The fact is Bobby Hull, Gordie Howe, or Tim Horton were freakish individuals. Far stronger than even the average athlete with 10 years of weight training even if their training consisted of throwing hay or drinking beer. Some people are just freakishly strong. Without any weight lifting at all. Look at Eric Lindros. He is going to be a massive physical specimen if he lifts weights 2 hours a day or if he eats at Taco Bell and doesn't ever lift a barbell.
I'll go on record as believing Orr, Gretzky, Howe, Jagr, Mario, Howe, Boby Hull dominate in any era, in any time. 20 years from now, today, 20 years ago or 60 years ago. They would throw on the new equipment and adapt in a week or 2 to the new strategies and coaching and be the best players any time any where. All you would need to do is throw them in a time machine, give them new equipment and let them watch a half dozen games and then they adapt almost immediately.